Problem: In his geometry class, William took 4 quizzes. His scores were 81, 77, 83, and 91. What was his average score on the quizzes?
Answer: The average is the sum of his scores divided by the number of scores. There are 4 scores and their sum is $81 + 77 + 83 + 91 = 332$ His average score is $332 \div 4 = 83$.